In a one-pipe heating system with a condensing boiler, the key to efficiency lies in keeping the returning water temperature low. Condensing boilers work best when the water coming back to the boiler is cool, ideally below 54°C (130°F). This allows the boiler to extract more heat from the exhaust gases, saving energy.
To make sure it works well, you need to ensure the boiler isn't too big for the space it heats. If it's too large, it might turn on and off too often, which isn't efficient. Also, how the system is set up matters — things like making sure the pipes are insulated and the radiators are the right size can help. Regular maintenance is also important. Keeping the boiler and system in good shape ensures it keeps working efficiently over time.